Association between the patterns of large-vessel lesions and treatment outcomes in patients with large-vessel giant cell arteritis.

OBJECTIVES: We aimed to identify associations between patterns of large-vessel lesions of large-vessel giant cell arteritis (LV-GCA) and treatment outcomes. METHODS: We extracted data on 68 newly diagnosed patients with LV-GCA from a retrospective, multi-centric, nationwide registry of GCA patients treated with glucocorticoids between 2007 and 2014. Patients with aortic lesions were identified based on the findings from contrast-enhanced computed tomography, magnetic resonance imaging, or positron emission tomography-computed tomography (Group 2, n = 49). Patients without aortic lesions were subdivided into LV-GCA with or without subclavian lesions defined as Group 1 (n = 9) or Group 3 (n = 10), respectively. The primary outcome evaluation was failure to achieve clinical remission by Week 24 and/or relapse within 104 weeks. RESULTS: The mean age and proportion of patients with cranial lesions and polymyalgia rheumatica in Group 2 were numerically lower than in the other two groups. Large-vessel lesions in Group 3 included carotid, pulmonary, renal, hepatic, or mesenteric lesions. The cumulative rate of poor treatment outcomes >2 years was 11.1%, 55.3%, and 88.0% in Groups 1, 2, and 3, respectively (by Kaplan-Meier analysis). The mean time to poor outcome was significantly different between the groups. CONCLUSIONS: Classification by subclavian and aortic lesions may be useful to determine treatment strategy.

Three Autopsy Cases of Non-Meningococcal Waterhouse-Friderichsen Syndrome with Hypoplastic Spleen or Post-Splenectomy Status.

We report three cases of Waterhouse-Friderichsen syndrome (WFS) that were confirmed during forensic autopsies. Case 1 involved a man in his 50s post-splenectomy. Bacteriological examination revealed Streptococcus pneumoniae (S. pneumonia). The patient was considered to have died of asphyxiation after aspirating vomit. Case 2 involved a man in his 40s. Bacteriological examination again revealed S. pneumoniae. Histopathological examination showed hypoplasia of the spleen. This patient was considered to have died of multiple-organ failure due to sepsis, disseminated intravascular coagulation, and WFS. Case 3 involved a post-splenectomy woman in her 60s with a history of systemic lupus erythematosus. Bacteriological examination revealed Streptococcus oralis. This patient was considered to have died of multiple-organ failure due to sepsis, disseminated intravascular coagulation, and WFS. These three cases were included among forensic autopsies conducted in the last 5 years. WFS has been considered a rare disease, but may be more frequent than previously assumed. If a mildly ill patient displays a sudden change in status and dies within a short period of time, we consider it necessary to perform not only bacteriological examinations, but also histopathological examination of the spleen during autopsy.

Gadolinium-enhanced magnetic resonance imaging in shoulders contributes accurate diagnosis and predicting recurrence to patients with polymyalgia rheumatica.

OBJECTIVES: We aimed to evaluate whether gadolinium-enhanced magnetic resonance imaging (MRI) in shoulders can contribute to more accurate diagnosis and prediction of recurrence in patients with polymyalgia rheumatica (PMR). METHODS: Gadolinium-enhanced MRI and ultrasonography (US) in shoulders were performed in the patients who had bilateral shoulders pain and fulfilled the Bird's Classification Criteria between June 2012 and June 2018. PMR was clinically diagnosed by at least two rheumatologists. MRI and US findings assessed by independent radiologists were compared between the PMR or non-PMR patients. PMR patients were treated with 20 mg/day of prednisolone and were followed-up until June 2019 to determine any recurrences of the disease. RESULTS: PMR was diagnosed in 58 of 137 patients received gadolinium-enhanced MRI and US examinations. Enhancement of joint capsule, enhancement of rotator cuff tendon and focal bone oedema in humerus heads were frequently found in the PMR patients. If the three findings were used in combination to diagnose PMR, MRI had 76% sensitivity and 85% specificity, higher compared to US findings, which had 50% sensitivity and 72% specificity. During follow-up, PMR recurred in 24 patients. Patients with recurrent PMR were younger in age, had less enhancement of rotator cuff tendon and more synovial hypertrophy findings on their MRI. CONCLUSIONS: Gadolinium-enhanced MRI could display capsulitis, rotator cuff tendonitis and focal bone oedema in humerus heads that was sensitive and specific to patients with PMR, improving diagnostic accuracy in PMR. Rotator cuff tendonitis and synovial hypertrophy on MRI could help predict recurrence in PMR.

Genetic determinants and an epistasis of LILRA3 and HLA-B*52 in Takayasu arteritis.

Takayasu arteritis (TAK) is a systemic vasculitis with severe complications that affects the aorta and its large branches. HLA-B*52 is an established susceptibility locus to TAK. To date, there are still only a limited number of reports concerning non-HLA susceptibility loci to TAK. We conducted a genome-wide association study (GWAS) and a follow-up study in a total of 633 TAK cases and 5,928 controls. A total of 510,879 SNPs were genotyped, and 5,875,450 SNPs were imputed together with HLA-B*52. Functional annotation of significant loci, enhancer enrichment, and pathway analyses were conducted. We identified four unreported significant loci, namely rs2322599, rs103294, rs17133698, and rs1713450, in PTK2B, LILRA3/LILRB2, DUSP22, and KLHL33, respectively. Two additional significant loci unreported in non-European GWAS were identified, namely HSPA6/FCGR3A and chr21q.22. We found that a single variant associated with the expression of MICB, a ligand for natural killer (NK) cell receptor, could explain the entire association with the HLA-B region. Rs2322599 is strongly associated with the expression of PTK2B Rs103294 risk allele in LILRA3/LILRB2 is known to be a tagging SNP for the deletion of LILRA3, a soluble receptor of HLA class I molecules. We found a significant epistasis effect between HLA-B*52 and rs103294 (P = 1.2 × 10-3). Enhancer enrichment analysis and pathway analysis suggested the involvement of NK cells (P = 8.8 × 10-5, enhancer enrichment). In conclusion, four unreported TAK susceptibility loci and an epistasis effect between LILRA3 and HLA-B*52 were identified. HLA and non-HLA regions suggested a critical role for NK cells in TAK.

An Autopsy Case of Spontaneous Coronary Artery Dissection With Eosinophilic Coronary Periarteritis and Degeneration of Medial Smooth Muscles.

ABSTRACT: A 45-year-old woman with no known medical history died suddenly shortly after complaining of anterior chest discomfort. The autopsy revealed a dissection at the anterior descending branch of the left coronary artery, and eosinophilic adventitial inflammation was observed both in the right coronary artery and in the vicinity of the dissection. Furthermore, there was degeneration of the tunica media in the right coronary artery, and this was thought to be a predissection lesion. In the degenerated area of the tunica media, probable apoptosis of smooth muscle cells was noted, suggesting that the degeneration was not due only to the effect of eosinophilic lytic enzymes. These findings also indicated that eosinophilic infiltration preceded the dissection. Eosinophilic infiltration around the coronary arteries is occasionally observed in cases of sudden death, but although it might be associated with the death, the pathological mechanism is yet to be elucidated. Eosinophilic periarteritis has also been observed around the site of spontaneous coronary artery dissection, although a causal relationship is unproven. The histopathology of this case indicated that the eosinophilic infiltration preceded the dissection. Detailed pathological findings are presented, together with a review of the literature.

Efficacy and safety of sodium RISedronate for glucocorticoid-induced OsTeoporosis with rheumaTOid arthritis (RISOTTO study): A multicentre, double-blind, randomized, placebo-controlled trial.

OBJECTIVE: No evidence has shown the efficacy of Sodium Risedronate (Risedronate) for glucocorticoid-induced osteoporosis (GIO) in patients with Rheumatoid arthritis (RA). The aim of this study was to explore the effectiveness and safety of Risedronate for GIO complicated with RA. METHODS: This was a six-month randomized, double-blind, placebo-controlled trial of 95 patients with GIO complicated with RA from 19 centers. The primary endpoint was the change from baseline in lumbar spine bone mineral density (L-BMD). Secondary endpoints included changes in femoral neck and total hip BMD and bone turnover markers, as well as rheumatoid arthritis Disease Activity Score with 28-joint counts. Incident of non-traumatic spine fractures and adverse events were tracked as safety endpoints. RESULTS: Increase in L-BMD was significantly greater in the Risedronate group compared to the Placebo group (Risedronate: 3.49% [95% CI: 1.92-5.05] vs Placebo: 0.12% [95% CI: -2.07 to 2.30], p < .0001). No significant difference was found in the femoral neck and total hip BMD. Although adverse events were observed in 28 patients, none were considered serious. Non-traumatic vertebral fractures were identified in 10 patients. CONCLUSION: Risedronate was effective in increasing L-BMD and was well tolerated in patients with GIO complicated with RA.

Pathogenic roles of anti-C1q antibodies in recurrent pregnancy loss.

Recurrent pregnancy loss (RPL) is often considered idiopathic, however excessive complement activation has been observed in pregnancy related manifestations. Anti-C1q antibodies (anti-C1q) are associated with the activation of complement pathway in lupus patients, while it remains unclear in RPL. Firstly, we showed that both the prevalence and titre of anti-C1q were significantly higher in unexplained RPL than in healthy parous individuals. Secondly, we established the murine model of anti-C1q induced pregnancy loss using a monoclonal anti-mouse C1q antibody, JL-1. In mice treated with JL-1, high ratio of pregnancy loss and fetal growth restriction were frequently observed and complement activation occurred. C5a receptor (C5aR) blockade cancelled these pathogenic changes in mice treated with JL-1. In conclusion, our study reveals an association between the prevalence of anti-C1q and RPL. Additionally, our murine model has indicated that anti-C1q can induce reproductive failure, which might be ameliorated by therapy targeting the C5-C5aR axis.

Systematic review and meta-analysis for 2017 clinical practice guidelines of the Japan research committee of the ministry of health, labour, and welfare for intractable vasculitis for the management of ANCA-associated vasculitis.

OBJECTIVES: To provide evidence for the revision of clinical practice guideline (CPG) for the management of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) by the Japan Research Committee for Intractable Vasculitis. METHODS: PubMed, CENTRAL, and the Japan Medical Abstracts Society were searched for articles published between January 1994 and January 2015 to conduct systematic review (SR), and the quality of evidence was assessed with GRADE approach. RESULTS: Nine randomized controlled trials (RCTs) and two non-RCTs were adopted for remission induction therapy, three RCTs and two non-RCTs for plasma exchange, and five RCTs and one non-RCT for remission maintenance therapy. A significant difference was found in efficacy and safety for the following comparisons. In the non-RCT adopted for remission induction therapy, glucocorticoid (GC) + cyclophosphamide (CY) was significantly superior to GC monotherapy regarding remission. GC + intravenous CY for remission induction therapy was superior to GC + oral CY regarding death at one year, serious adverse events, and serious infection. Concomitant use of plasma exchange for remission induction therapy of AAV with severe renal dysfunction reduced risk of end-stage renal disease versus non-users at month 3. CONCLUSION: This SR provided necessary evidence for developing CPG for the management of ANCA-associated vasculitis.

Splicing variant of WDFY4 augments MDA5 signalling and the risk of clinically amyopathic dermatomyositis.

OBJECTIVES: Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare autoimmune diseases in which both genetic and environmental factors play important roles. To identify genetic factors of IIM including polymyositis, dermatomyositis (DM) and clinically amyopathic DM (CADM), we performed the first genome-wide association study for IIM in an Asian population. METHODS: We genotyped and tested 496 819 single nucleotide polymorphism for association using 576 patients with IIM and 6270 control subjects. We also examined the causal mechanism of disease-associated variants by in silico analyses using publicly available data sets as well as by in in vitro analyses using reporter assays and apoptosis assays. RESULTS: We identified a variant in WDFY4 that was significantly associated with CADM (rs7919656; OR=3.87; P=1.5×10-8). This variant had a cis-splicing quantitative trait locus (QTL) effect for a truncated WDFY4isoform (tr-WDFY4), with higher expression in the risk allele. Transexpression QTL analysis of this variant showed a positive correlation with the expression of NF-κB associated genes. Furthermore, we demonstrated that both WDFY4 and tr-WDFY4 interacted with pattern recognition receptors such as TLR3, TLR4, TLR9 and MDA5 and augmented the NF-κB activation by these receptors. WDFY4 isoforms also enhanced MDA5-induced apoptosis to a greater extent in the tr-WDFY4-transfected cells. CONCLUSIONS: As CADM is characterised by the appearance of anti-MDA5 autoantibodies and severe lung inflammation, the WDFY4 variant may play a critical role in the pathogenesis of CADM.

Time-Dependent Changes in Local and Serum Levels of Inflammatory Cytokines as Markers for Incised Wound Aging of Skeletal Muscles.

Wound age estimation is an important research field in forensic pathology. The expression levels of cytokines in the incised skeletal muscle were analyzed using a mouse model to explore the applicability for wound aging. A 5-mm long incisional wound was made at the biceps femoris muscle, and the muscle and serum were sampled at 6, 12, 24 and 48 hours after injury. Using a multiplex bead-based immunoassay, we measured the tissue levels of nine cytokines (IL-1ß, IL-6, IL-7, CCL2, CCL3, CCL4, CXCL1, CXCL2, and CXCL10), which are all involved in the pathways of inflammatory response and tissue injury. Immunoassay of post-injury muscle samples revealed significant increases in the levels of six cytokines, except for CCL3, CCL4 and IL-7, at 6 hours after injury. The elevated tissue levels of these six cytokines were maintained during 48 hours after injury, although the levels of IL-6 and CXCL1 were significantly decreased at 12 hours. In case of CCL3, its tissue levels were increased only at 12 hours. By contrast, CCL4 and IL-7 levels were increased only at 48 hours. Moreover, serum levels of most cytokines, except for CXCL1, remained unchanged during 24 hours after injury, followed by significant increases at 48 hours. Serum CXCL1 levels were increased at 6 hours and then decreased to the basal levels. Thus, the significant increase in the muscle levels of CXCL1 and IL-7 was observed at 6 and 48 hours after injury, respectively. Measuring muscle CXCL1 and IL-7 levels is helpful for estimating incised wound aging.

Evaluation of the alternative classification criteria of systemic lupus erythematosus established by Systemic Lupus International Collaborating Clinics (SLICC).

OBJECTIVE: To evaluate the performance of the 2012 Systemic Lupus International Collaborating Clinics criteria (SLICC-12) on classifying systemic lupus erythematosus (SLE) in an uncontrolled multi-centered study with real-life scenario of the patients in Japan. METHODS: This study comprised 495 patients with SLE or non-SLE rheumatic diseases and allied conditions from 12 institutes in Japan. Chart review of each patient was performed by the 27 expert rheumatologists and diagnosis of 487 cases reached to the consensus. Value of the SLICC-12 on SLE classification was analyzed comparing with the 1997 revised American College of Rheumatology SLE classification criteria (ACR-97) employing the expert-consented diagnoses. RESULTS: Compared to the ACR-97, the SLICC-12 had a higher sensitivity (ACR-97 vs. SLICC-12: 0.88 vs. 0.99, p < .01) and comparable specificity (0.85 vs. 0.80). The rate of misclassification (0.14 vs. 0.11) or the area under the receiver operating characteristic curves (0.863 vs. 0.894) was not statistically different. In the cases that diagnoses corresponded in high rates among experts, both criteria showed high accordance of SLE classification over 85% with the expert diagnoses. CONCLUSION: Although employment of SLICC-12 for the classification for SLE should be carefully considered, the SLICC-12 showed the higher sensitivity on classifying SLE in Japanese population.

Transethnic meta-analysis identifies GSDMA and PRDM1 as susceptibility genes to systemic sclerosis.

OBJECTIVES: Systemic sclerosis (SSc) is an autoimmune disease characterised by skin and systemic fibrosis culminating in organ damage. Previous genetic studies including genome-wide association studies (GWAS) have identified 12 susceptibility loci satisfying genome-wide significance. Transethnic meta-analyses have successfully expanded the list of susceptibility genes and deepened biological insights for other autoimmune diseases. METHODS: We performed transethnic meta-analysis of GWAS in the Japanese and European populations, followed by a two-staged replication study comprising a total of 4436 cases and 14 751 controls. Associations between significant single nuclear polymorphisms (SNPs) and neighbouring genes were evaluated. Enrichment analysis of H3K4Me3, a representative histone mark for active promoter was conducted with an expanded list of SSc susceptibility genes. RESULTS: We identified two significant SNP in two loci, GSDMA and PRDM1, both of which are related to immune functions and associated with other autoimmune diseases (p=1.4×10-10 and 6.6×10-10, respectively). GSDMA also showed a significant association with limited cutaneous SSc. We also replicated the associations of previously reported loci including a non-GWAS locus, TNFAIP3. PRDM1 encodes BLIMP1, a transcription factor regulating T-cell proliferation and plasma cell differentiation. The top SNP in GSDMA was a missense variant and correlated with gene expression of neighbouring genes, and this could explain the association in this locus. We found different human leukocyte antigen (HLA) association patterns between the two populations. Enrichment analysis suggested the importance of CD4-naïve primary T cell. CONCLUSIONS: GSDMA and PRDM1 are associated with SSc. These findings provide enhanced insight into the genetic and biological basis of SSc.

The first genome-wide association study identifying new susceptibility loci for obstetric antiphospholipid syndrome.

Antiphospholipid syndrome (APS) is the most important treatable cause of recurrent pregnancy loss. The live birth rate is limited to only 70-80% in patients with APS undergoing established anticoagulant therapy. Lupus anticoagulant (LA), but not anticardiolipin antibody (aCL), was found to predict adverse pregnancy outcome. Recent genome-wide association studies (GWAS) of APS focusing on aCL have shown that several molecules may be involved. This is the first GWAS for obstetric APS focusing on LA. A GWAS was performed to compare 115 Japanese patients with obstetric APS, diagnosed according to criteria of the International Congress on APS, and 419 healthy individuals. Allele or genotype frequencies were compared in a total of 426 344 single-nucleotide polymorphisms (SNPs). Imputation analyses were also performed for the candidate regions detected by the GWAS. One SNP (rs2288493) located on the 3'-UTR of TSHR showed an experiment-wide significant APS association (P=7.85E-08, OR=6.18) under a recessive model after Bonferroni correction considering the number of analyzed SNPs. Another SNP (rs79154414) located around the C1D showed a genome-wide significant APS association (P=4.84E-08, OR=6.20) under an allelic model after applying the SNP imputation. Our findings demonstrate that a specific genotype of TSHR and C1D genes can be a risk factor for obstetric APS.

ß2-Glycoprotein I/HLA class II complexes are novel autoantigens in antiphospholipid syndrome.

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thrombosis and/or pregnancy complications. ß2-glycoprotein I (ß2GPI) complexed with phospholipid is recognized as a major target for autoantibodies in APS; however, less than half the patients with clinical manifestations of APS possess autoantibodies against the complexes. Therefore, the range of autoantigens involved in APS remains unclear. Recently, we found that human leukocyte antigen (HLA) class II molecules transport misfolded cellular proteins to the cell surface via association with their peptide-binding grooves. Furthermore, immunoglobulin G heavy chain/HLA class II complexes were specific targets for autoantibodies in rheumatoid arthritis. Here, we demonstrate that intact ß2GPI, not peptide, forms a complex with HLA class II molecules. Strikingly, 100 (83.3%) of the 120 APS patients analyzed, including those whose antiphospholipid antibody titers were within normal range, possessed autoantibodies that recognize ß2GPI/HLA class II complexes in the absence of phospholipids. In situ association between ß2GPI and HLA class II was observed in placental tissues of APS patients but not in healthy controls. Furthermore, autoantibodies against ß2GPI/HLA class II complexes mediated complement-dependent cytotoxicity against cells expressing the complexes. These data suggest that ß2GPI/HLA class II complexes are a target in APS that might be involved in the pathogenesis.

Autoantibodies to IgG/HLA class II complexes are associated with rheumatoid arthritis susceptibility.

Specific HLA class II alleles are strongly associated with susceptibility to rheumatoid arthritis (RA); however, how HLA class II regulates susceptibility to RA has remained unclear. Recently, we found a unique function of HLA class II molecules: their ability to aberrantly transport cellular misfolded proteins to the cell surface without processing to peptides. Rheumatoid factor (RF) is an autoantibody that binds to denatured IgG or Fc fragments of IgG and is detected in 70-80% of RA patients but also in patients with other diseases. Here, we report that intact IgG heavy chain (IgGH) is transported to the cell surface by HLA class II via association with the peptide-binding groove and that IgGH/HLA class II complexes are specifically recognized by autoantibodies in RF-positive sera from RA patients. In contrast, autoantibodies in RF-positive sera from non-RA individuals did not bind to IgGH/HLA class II complexes. Of note, a strong correlation between autoantibody binding to IgG complexed with certain HLA-DR alleles and the odds ratio for that allele's association with RA was observed (r = 0.81; P = 4.6 × 10(-5)). Our findings suggest that IgGH complexed with certain HLA class II alleles is a target for autoantibodies in RA, which might explain why these HLA class II alleles confer susceptibility to RA.

Effectiveness of whole-body magnetic resonance imaging for the efficacy of biologic anti-rheumatic drugs in patients with rheumatoid arthritis: A retrospective pilot study.

OBJECTIVES: To evaluate the scoring of whole-body magnetic resonance imaging (WBMRI) for efficacy assessment in rheumatoid arthritis (RA) patients receiving biological disease-modifying anti-rheumatic drugs (bDMARDs). METHODS: Thirty consecutive RA patients receiving bDMARDs were included in this retrospective study. Contrast WBMRI was performed before and 1 year after bDMARDs initiation. RESULTS: At baseline, mean age was 57.1 years and mean disease duration was 3.0 years. Median disease activity score in 28 joints improved from 5.1 to 2.1. Treatment with bDMARDs improved mean whole-body synovitis score from 31.2 to 23.2 and median whole-body bone-edema score from 11 to 3. Whole-body bone-erosion score improved in seven patients and deteriorated in 17 patients. Logistic regression analysis identified whole-body synovitis score as a poor prognostic factor for whole-body bone-erosion progression. Bone-edema score in individual bones was identified as a poor prognostic factor for the progression of bone-erosion. Changes in hand synovitis score correlated with those of other joints, but neither changes in bone-edema nor erosion score of hands correlated with those of other joints in WBMRI. CONCLUSIONS: WBMRI scoring may be a novel useful tool to evaluate the efficacy of anti-rheumatic drugs, as well as a potential predictor of joint prognosis, in patients with RA.

Bi-ventricular interplay in patients with systemic sclerosis-associated pulmonary arterial hypertension: Detection by cardiac magnetic resonance.

OBJECTIVES: Pulmonary arterial hypertension (PAH) associated with systemic sclerosis (SSc) has a poor prognosis compared to PAH associated with other connective tissue diseases (CTD). The objective of this study was to examine the difference in hemodynamic state between SSc-PAH and other CTD-PAH by performing cardiac magnetic resonance (CMR) imaging. METHODS: A single center retrospective analysis was conducted comprising 40 consecutive CTD patients who underwent right heart catheterization and CMR at the same period from January 2010 to October 2015. RESULTS: Thirty-two patients had pre-capillary pulmonary hypertension. Of these, 15 had SSc and 17 had other CTD. CMR measurements, particularly the ratio of right to left end-diastolic volume (RVEDV/LVEDV), correlated well with mean pulmonary arterial pressure (mPAP). Conversely, RVEDV/LVEDV and mPAP correlated differently in SSc and non-SSc patients. In SSc patients, the ratio of RVEDV/LVEDV to mPAP was significantly higher compared to non-SSc patients. In the follow-up study, 2 SSc patients exhibited increased RVEDV/LVEDV in spite of decreased mPAP following treatment. Kaplan-Meier analysis revealed poor prognosis of patients with increased RVEDV/LVEDV following treatment. CONCLUSIONS: Our data indicated that altered bi-ventricular interplay detected at CMR may represent SSc-related cardiac involvement and reflect poor prognosis of SSc-PAH.

Autoantibodies against a complement component 1 q subcomponent contribute to complement activation and recurrent thrombosis/pregnancy morbidity in anti-phospholipid syndrome.

OBJECTIVE: To investigate the prevalence and significance of the autoantibodies against complement component 1 q subcomponent (C1q) in patients with APS. METHODS: In all, 40 consecutive primary APS patients, 42 patients with non-SLE CTDs and 20 SLE patients negative for aPL were enrolled in this retrospective analysis. Refractory APS was defined as a clinical status of recurring thrombosis or pregnancy morbidity during adequate secondary prophylaxis. An ELISA was used to measure serum levels of anti-C1q antibodies and anaphylatoxins (C3a, C4a). RESULTS: Anti-C1q antibodies were found in 36% (15/42) and 2.5% (1/40) of primary APS patients and controls, respectively. Among primary APS patients, anti-C1q antibody titres were significantly correlated with serum C4a levels (P = 0.013). Neither the prevalence nor the titre of anti-C1q antibodies was associated with any specific clinical manifestations of APS, nor titres of aPL. Refractory APS patients (n = 10) had a higher prevalence of anti-C1q antibodies (9/10 vs 6/32, P = 0.01) than APS patients without recurrence (n = 32). CONCLUSION: Anti-C1q antibodies are associated with complement activation in APS and may contribute to the pathogenesis, particularly in refractory cases.